The municipality is located some 14 km from the provincial capital, Vitoria. It has an area of 19.95 km², and a population (2004) of some 1,919 inhabitants.

Alegría-Dulantzi municipality is divided into two sub-areas, or communes (concejos or kontzejuak). By far the larger of the two is the municipal centre and township of Alegría-Dulantzi itself, which accounts for some 95% of the municipality's population. The municipality also controls a small exclave located to the southeast, called Egileta, which is surrounded by a neighbouring municipality.